Process for melting and working quartz glass.



H. MEHNER. PROCESS FOR MELTING AND WORKING QUARTZ GLASS. APPLICATION FILBp AUG.14, 1906.

93 l ,945. Patented Aug. 24, 1909.

UNITED STATES PATENT oEEroE. A'

HJEBIAANN' HEHNEB., 0F FBIEDENAUfNEAR BERLIN, GERMANY.

Specilcation of Letters Patent.

' PROCESS FOR MELTING AND WORKING QUARTZ GLASS.

application led August 14, i906. Serial No. 380,538.

To all whom 'it may concern:

13e it known that I,.HERMANN ME'HNER, of Frledenau, near Berlin, Germany, have inlvented certain new and useful Improvements.

in Processes' for Melting andv Working Quartz Glass, of which thel following is a specification.

The object of--my invention is to produce 'articles of molten quartzeasily and rapidly.`

To this end my invention consists in a process of melting quartz by means of the Arays lof electric arcs.

The production of glass from quartz by melting lthe quartzv immediately in or near the electric arc is a diflicult matter, `as the ,temperature of the electric arc is too high.

For this reason I separate the hearth, on

which the quartz is t'o be melted, from the` electric arc, and only concentrate the rays of the electric arc upon the hearth by suitable reflectors. I, at the same time, take care that no excessive concentration of the heat'.

can take place.

As the quartz has the quality of evaporatr- ".ing under ordinary pressure near the melting oint I take provisionsfor ee'cting the melting of the quartz at rst under pressure,

-whereby I amr able to liquefy the quartz without any evaporation worth mentioning. To attain this thinly liquid state of the quartz is of great importance for the production of glass from quartz, as only then the air contained Vin the quartz can escape. As soon as I have in this way reached this highly liquid state of the'quartz by melting it, I cool the same again down to that tem` perature at which it assumes, under ordinary pressure, a consistence, in which it can be worked, the same as ordinary glass, into articles of any shape. This working of the molten quartz is carried on underordinary pressure.

In-order that my invention and the carry ing out 'of the same may be clearly understood by those acquainted with this-art I have shown on the drawing an apparatus by which'the object of this invent-ion can be attained The drawing represents a melting-furnace inaJ vertical section.

On the drawing the wall of the furnace 1s marked.with1.. This wall of the furnace has the form of an ellipsoid, from which the lower part is cut off. The cut oil' ipart 1 of the ellipsoid, which forms the space for ellipsoid is placed the electric arc.8 between the two electrodes 9, 10. The electrodes 9 and 10 pass' through o enin s in the wall of'- the ellipsoid 1.A Thee lipsoid 1 is on its inside r'etlective, and preferably consists of a refractory metal, for instance nickel. Other materials may however also be used, for instance quartz-glass lined with'a reflecting covering. The surface of the ellipsoid is represented as fitted withfa bar 11, which carries a cup 12 serving to catch-impurities whichzfall off from the points of the elec ytrodes.

The wall of the ellipsoids coat/ed on the outside with a heat-lnsulating substance 13. In 'the wall ofthe ellipsoid are provided several openings.

sented opened. Through this opening passes the shaft of a glass4 blowin' pipe 1 .for working the molten quartz-g ass in the interior of the ellipsoidal furnace-s ace. Two further openings are represente -as closed by closing-devlce's 16, 17. The opening closed by the closing-device 16, which communicates with the opening 14, represented as open', serves to take out the glass-blowing pipe 15 together withthe object of quartz On the drawing a part 5 of the quart-z? PatentedAug. 2,4, 1909.

Of these openings one, which is marked with 14, is repreproduced by it. The opening closed by the closing-device 17 serves to take out the molten quartz by means of a suitable device.

18 isa window serving to observe the process in the-interior of the furnace. .Thiswindow is of very refractory glass, such as quartz glass'coa-ted with a translucent reflecting' layer 19, such as a thin ilm of latinuln. 20 is an outside jacket or mant e,`wh.ich is air-tightly united by means of bolts, with the border 21 ot the hearth-kettle 4. Through the mantle 20 are guided airtightly the electrodes 9,; 10, for which purpose there areprovided packing-rings 22,23. 24 is a socket opening intothe' interior of the mantle 20, to which is connected, through a tube 25, a bottle '26, which is presumed to be ille'd with a compressed gas, for linstance-carbonic acid. A

27 is an inspectionopening in the mantle eo.. with es' is marked a hood which carare marked openings in the lower part of the wall of the ellipsoid 1.

The apparatus Works as follows: 'Through y the opening of the ellipsoid 1, closed by the device 17, quartzose sand or other quartzose material is fed into the kettle 4. ,Hereupon the closing-device 17 is again inserted into the ellipsoidal mantle l, and also all the other openings of the ellipsoidal mantle are closed', and the outer mantle 20 is thereupon placed over the ellipsoid 1. The mantle 20 is hereby assumed consisting of two parts,

vthe planeof division being parallel to the plane of the paper of the drawing and-not' visible in the drawing. Now the electric arc 8 is generated in the focus 7 of the ellipsoid 1 between the electrodes' 9, 10. The rays emanating from the electric. arc are cast 'by the ellipsoid surface 1 upon. the lower focus o', as far as they do not fall directly upon the quartzose material. Under the influence of the'rays fallin upon the quartzose mass, this mass is great y heated, whereas the furnace room inclosed by ellipsoid 1 is kept at a `comparatively low temperature on account of the concentrationl of h eat only in the focus of the reflecting ellipsoid. -As soon as a considerable temperature has'been reached, which willV be when clouds commence to rise from the mass, the furnace is put under pressure, which is effected `by establishing aconnection 'between the interior of the bottle 2G and the interior'o'f the mantle 20. The production of an increased pressure in the furnace makes it possible to increase the temperature of the softened quart-zose mass, without any evaporation of the same taking place. In consequence of this increased tem` perature the quartzose mass gradually becomes highlyliquid and in this state it allows all the air in'cbsed maitto escape. The pressure which is necessary in order to attain this object may vary according to circumstances. Higher pressure corresponds to a shorter"l length of the purifying process andvice versa: Therefore it is advisable to use higher pressure in' connection with a small furnace and lower pressure in connection'` with large furnaces. A pressure of 400 to 500 pounds to the square inch will be Jsatisfactory unde-r ordinary conditions. As soonas the quartzose mass has been subjected for x a suiclent lengthof time to the urifying process the temperature-inthe urnace is v reduced, which is efected by suitable influences on' the electric arc. The molten mass "soon as this state is reached the communication between the interior of 'the mantle 20 with the interior of the bottle 26 is interrupted and the mantle 20 removed. After removing the mantle 20 the ordinary atmosphericpressure is restablished in the furnace. Now the hood 28 with the burner 29 is put upon the outer surface of the ellipsoid 1 and the burner, to which from any suitable place a combustible mixture of air and gas isv conveyed, is ignited. The waste gases escape at the bottom, partly through the opening 14, partly through openings 30 at the lower end of the ellipsoidal mantle 1. By the ventilation in a downward direction traces of clouds of quartz', which might be formed above the molten mass, are removed, so that the rays coming from the electric arc can freely penetrate into the quartzose mass and the furnace can be observed through the Window 18. y

By means of the pipe 15 molten quartz can be taken out and worked into objects in the same way as molten glass.

Fresh quartz can be admitted in any suitable manner, for inst-ance by opening the closing-device 17. v

The apparatus here described and illustrated in the drawings may be modified in different ways wit-hout departing from the principle of the invention. Thus for vinstance instead vof the ellipsoidal wall of the furnace a parabolic wall may b selected or a number of ellipsoid or parabolicA sections may be made to form thel vault of thefurnace. v

A noteworthy'peculiarity of the new lfurnace consists thereinthat the wall of the furnace is kept co'oler than the molten material. By a suitable application of 'a heatinsulating mass 13 theinterior of the furnace is kept so hot that it is possible to work the molten quartz mass also abovevthe surface of the hearth on which the rays othe electric arc are Concentrated, and so that not too mjuch heat is lost by radiation.L

n 'What I` claim as my invention andA desimtO secure by United States Letters Patent is- 1. Process of melting and working quartz glass consisting in heating quartz up to its melting point, subjecting the molten quartz to vpressure while being heated to a condi-y tion oflhi h liquidity, letting the massA cool down so ar that it remains homogeneously -molten and in working the molten mass at such condition of viscosity. Y

2. Process of melting and Vworking quartz glass consisting in exposin quartz,y under pressure higher than atmosp eric, to the action of the rays of electric arcs, which are concentrated byrelectors until the massof uartz has become highly.4 liquid, and vin t ereafter letting'the mass cool downl so far that it remains homogeneously molten, and in working the molten mass under atmospheric pressure.

3. Process of melting and Working quartz glass consisting in exposing quartz, under pressure higher than atmospheric, to the action of the rays of. electric arcs, which are,

concentrated by reflectors until the mass of quartz' has become highly liquid, and in thereafter letting the mass cool down so far that it remainshomogeneously molten, and

in working the molten mass under atmospheric pressure, while a ventilation from the top to the bottom is produced in the furnace. 4. Process of melting and working quartz glass consisting in heating quartzose material by an electric arc in a furnace provided With reflecting surfaces, keeping the material under pressure when molten to a condition of hi h liquidity, letting thereafter the mass coo down to a conditlon of less liquidity and Working it at such condition of viscosity under ordinary pressure.

In testimony whereof 1 have signed this specification in. the presence of two subscribing witnesses.

HERMANN MEHNER. Witnesses:

' HENRY HASPER,

' WILLIAM MAYNER. 

